equation solving with 3 variables and 4 equations

Hello,

I am having trouble with my code depending upon the inputs. Here is the code: clc;

clear;

sx=input('sigma_x=');

sy=input('sigma_y=');

sz=input('sigma_z=');

txy=input('tau_xy=');

tyz=input('tau_yz=');

tzx=input('tau_zx=');

A = [sx txy tzx; txy sy tyz; tzx tyz sz];

[V,D] = eig(A);

[d,ind] = sort(diag(D));

s1 = d(3)

s2 = d(2)

s3 = d(1)

syms i1 m1 n1

eq1 = ((sx - s1)*i1) +(txy*m1) + (tzx*n1)==0;

eq2 = (txy*i1) +((sy-s1)*m1) + (tyz*n1)==0;

eq3 = (tzx*i1) + (tyz*m1) + ((sz-s1)*n1)==0;

eq4 = (i1)^2+(m1)^2+(n1)^2==1;

[i1,m1,n1] = solve(eq1,eq2,eq3,eq4,i1,m1,n1);

i1= vpa(i1(1))

m1= vpa(m1(1))

n1= vpa(n1(1))

When sx=50, sy=100, sz=0, txy=-60, tyz=0, and tzx=0 the code works fine and I find my values for i1, m1, and n1.

When sx=-40, sy=100, sz=30, txy=-50, tyz=12 , and tzx =0 the equations (eq1,eq2,eq3) have these crazy values and I do not understand why.

Please let me know if you know how to resolve this issue!! Thank you for your help.